Description of Prior Art
Containers filled with freezable liquid for use as refrigeration or temporary cooling, are available at most retail outlets today. Described as "reusable ice substitutes", they are either soft flexible plastic envelopes or semi-rigid plastic blocks. The soft plastic envelopes are weak and insecure and can carry biological contaminants. The plastic block has a thick plastic container which insulates the frozen liquid from the space to be cooled, bulges and deforms when frozen, and can carry biological contaminants on the plastic exterior.